The major objectives of the proposed research are (a) to develop further and extend an experimental technique that will (b) provide systematic quantitative assessment of visual aspects of social perception in comparative perspective with two species of nonhuman primates, the pigtail macaque (Macaca nemestrina) and the bonnet macaque (M. radiata). The technique proposed involves the combination of an operant picture presentation procedure with behavioral observations during the presentation of standardized color television videotapes of social partners engaged in specified behaviors. Specific studies are designed to assess (a) the capacity to recognize conspecific individuals, (b) the role of individual recognition and visual attention in the organization of a hierarchical social structure, and (c) the role of specific communication in establishing dominance relationships between individuals. The data obtained in the proposed research will provide an empirical foundation for further studies of social perception in macaques, as well as a conceptual basis for theories of social perception in nonhuman primates.